• Journal of Environmental Health Sciences
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• v.34 no.1
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• pp.86-94
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• 2008

Lake Shiwha, an artificial lake located near metropolitan Seoul, offers a unique water environment and has been suspected to have high levels of chemical and microbiological contaminations. Lake Shiwha was originally connected to the sea but currently has four major surface water inputs from agricultural, municipal, industrial areas and in addition an occasional inflow from the sea. The objectives of this study are to investigate the relative contribution of microbial contaminants from each of the inflowing surface waters and to identify appropriate microbial indicator organisms in this unique water environment. We measured the levels of microbial contaminations in the four inflowing surface waters. A number of microbial indicator organisms including total coliform (TC), fecal coliform (FC), E. coli, Enterococci, somatic and male-specific coliphages were analyzed. Bacterial indicator microorganisms were detected and quantified by the $Colilert^{(R)},\;Enterolert^{(R)}$ kit. Surface water (50 l) was sampled by $ViroCap^{TM}\;5"$ cartridge filters and analyzed by the single agar layer method for detecting coliphages. The concentrations of TC, FC, E. coli, and Enterococci were 1543 CFU/100 ml${\sim}1.99{\times}10^6$ CFU/100 ml, 0 CFU/100 ml${\sim}202$ CFU/100ml, 0 CFU/100 ml${\sim}1.80{\sim}10^5$ CFU/100ml, 74 CFU/100 ml${\sim}3408$ CFU/100 ml, respectively. The male-specific and somatic coliphages were detected in three different inflowing surface waters. Isolated E. coli and Enterococci strains were further analyzed by 16s rDNA amplification and subsequent phylogenetic analysis from Jungwang-chun, Ansan-chun, Banwol-chun and penstock of inflowing surface water. Our results indicated that the concentrations of different fecal indicator microorganisms might not be highly correlated with each other. Multiple microbial indicator organisms should be used for monitoring microbial contamination and microbial source tracking methods.

• Food Science of Animal Resources
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• v.29 no.2
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• pp.269-277
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• 2009

This paper reports the results of the research on the effects of probiotic yogurt on the microbiological quality, pH, and sensorial characteristics of fresh chicken meat when packed with probiotic yogurt. The chicken meat pieces were packed with yogurt and were stored at $10^{\circ}C$ for 7 days. Samples were taken after 0, 2, 4, and 7 days of storage, and were analyzed for total bacterial count, E. coli, and coliform, and for the chemical parameters, including the pH. In the control group (packed without yogurt), the Pseudomonas species predominated when the spoilage was obvious after 4-day storage at $10^{\circ}C$. The yogurt-mixed chicken meat package was found to have a significantly lower total viable count and significantly fewer coliform bacteria during storage. Furthermore, the yogurt package showed a growth-inhibiting effect on the Salmonella typhimurium, which were inoculated into the chicken meat pieces for the study. The study findings indicate that probiotic yogurt can be used in packing fresh chicken meat to decrease the population of spoilage bacteria therein and to extend its shelf life.

• Korean Journal of Food Science and Technology
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• v.34 no.6
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• pp.962-968
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• 2002

Effects of gamma-irradiation of 1 to 10 kGy on the microbial growth, contents of amino acids, fatty acids, and free sugars, and changes in acid values in soybean powder were studied. Irradiation doses at $3{\sim}5\;kGy$ inhibited the mold growth completely in two kinds of imported soybean powders. Contents of sulfur-containing amino acids, such as cysteine, in both soybean powders decreased with irradiation, whereas no significant changes in free amino acid and fatty acid contents of both soybean powders were observed. Free sugar contents of stachyose and sucrose in Chinese soybean powder decreased with increasing irradiation dose level, whereas, those of other sugars remained unchanged. Results of this study confirm that $3{\sim}5\;kGy$ irradiation can be safely applied to apply to soybean powder without causing significant quality deteriorations microbiologically and chemically.

• Korean Journal of Agricultural Science
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• v.14 no.2
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• pp.318-328
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• 1987

The results of experiment to review the optimum pasteurization condition for the raw milk produced in Korea by using UHT procedure of $100-145^{\circ}C$, the changes in chemical composition, microbiological aspects and the keeping quality of the heat treated milk are summarized as follows: 1. In UHT milk sterilized at $100-145^{\circ}C$, the pH value decreased from 6.55 to 6.33 but protein, fat, lactose and ash did not show significance changes while casein nitrogen and non-protein nitrogen increased but non-casein nitrogen and filterable nitrogen decreased. 2. Calcium content decreased gradually from 119.8 mg/100 g of raw milk to 75.75 mg/100 g at $145^{\circ}C$ as the heat treatment increased and vitamin C decreased rapidly from 1.37 mg/100 ml to 0.82 mg/ 100 ml while artificial digestibility increased from 14.07% of raw milk to 26.0% as the heat treatment increased. 3. As the heat treatment increased, microorganism counts decreased to $0.5{\times}10^2/ml$ and were not found above $135^{\circ}C$ - coliforms and psychrotrophic bacteria from $100^{\circ}C$ thermoduric bacteria, thermophiles, mould and yeast from $125-130^{\circ}C$. Heat treatment above $135^{\circ}C$ showed 100% sterilization effect. 4. The result of preservation test for heat treated milk did not show any significant changes in titratable acidity and general composition at $4^{\circ}C$, $25^{\circ}C$ and $37^{\circ}C$ up to 15 days. Viable bacteria counts, coliforms and psychrotrophic bacteria were not found but loss of vitamin and increase in viable bacteria counts appeared after 20 days.

• Korean Journal of Agricultural Science
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• v.14 no.2
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• pp.309-317
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• 1987

The raw milk produced in Korea was heated at $70^{\circ}C$, $75^{\circ}C$, $80^{\circ}C$, $85^{\circ}C$, $90^{\circ}C$, $95^{\circ}C$ and $100^{\circ}C/15sec.$. The changes in chemical composition and microbiological aspects of the milk were summarized as following results: 1. In high temperature pasteurized milks as the heat treatment increased, pH value decreased but protein, fat, lactose and ash did not show significant changes in their contents while casein nitrogen and non-protein nitrogen increased but non-casein nitrogen and filterable nitrogen decreased in their contents. 2. Calcium content of raw milk decreased from 119.79mg/100g to 111.86mg/100g at $75^{\circ}C$ and to 106.24mg/100g at $100^{\circ}C$. Vitamin C decreased from $1.37mg/100m{\ell}$ of raw milk to $1.15mg/100m{\ell}$ at $75^{\circ}C$ and $0.94mg/100m{\ell}$ at $100^{\circ}C$. Artificial digestibility increased as the heat treatment got higher. 3. Viable bacteria counts decreased from $9.0{\times}10^3/m{\ell}$ at $75^{\circ}C$ to $3.4{\times}10^2/m{\ell}$ at $100^{\circ}C$. Coliforms were not found at $70^{\circ}C$ and thermoduric bacteria, thermophiles, psychrotrophic bacteria, mould and yeast decreased rapidly as the heat treatment increased. 4. The results of Keeping quality test for high temperature pasteurized milk showed that the' milks preserved at $25^{\circ}C$ and $37^{\circ}C$ were clotted just after 1 day but the milk preserved at $4^{\circ}C$ showed good shelf life which did not have any deterioration in titratable acidity, microorganisms and com positions.

• Journal of Food Hygiene and Safety
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• v.13 no.4
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• pp.319-331
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• 1998

The purposes of this study were to develop Hazard Analysis Critical Control Point plan applicable to cook/chilled Pork Bulkogi (broiled sliced pork with sauces) in school foodservice operations and to establish reasonable shelf-life limits by assessing food quality during chilled storage period of 5 days. During the product flow, time-temperature profile was recorded and microbiological analyses including mesophilic and psychrotrophic total plate counts, coliform, and fecal coliform and qualitative analyses of Salmonella and Listeria monocytogenes were done. Chemical analyses (pH, acid value, total volatile basic nitrogen), sensory evaluation, and quantitative analysis of thiamin were conducted for 5 days of chilled storage. The number of mesophiles in raw pork ($4.26{\pm}0.11\;Log\;CFU/g$), seasoning mixture ($5.97{\pm}O.04\;Log\;CFU/g$) and marinated pork ($5.56{\pm}0.21\;Log\;CFU/g$) were below the microbial standards for "requires further cooking" food items. Listeria monocytogenes was detected in seasoning mixture. After heating, the number of mesophiles ($5.17{\pm}0.04\;Log\;CFU/g$) were slightly reduced but it did not meet the microbial guidelines of $5\;Log\;CFU/g$ for "ready-to-eat" foods. No other microbes including pathogens were detected. By reheating the menu item after chilled storage, the number of mesophiles were reduced in every phase of 1st day ($4.62{\pm}0.22\;Log\;CFU/g$), 3rd day ($4.55{\pm}0.20\;Log\;CFU/g$) and 5th day ($4.25{\pm}0.16\;Log\;CFU/g$) of chilled storage, and the number of microbes was below the standard limits for "ready-to-eat" foods. At the fifth day of chilled storage, pH (p<0.05), acid value (p<0.01) and TVBN (p<0.05) showed significant increases. Sensory evaluation results did not show any significant change for 5 days of chilled storage. Thiamin content showed a decrease for 5 days of chilled storage. Consequently, the ideal shelflife recommended for Pork Bulkogi was within 3 days of chilled storage. CCPs for Pork Bulkogi were purchasing and receiving of raw meat and some seasoning ingredients, heating, chilling, chilled storage, reheating, and distribution.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.19 no.1
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• pp.20-26
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• 1986

Very little information is available in the literature on storage of fish sauce. Therefore, microbiological and chemical chracteristics during storage and quality of fish sauce were investigated and discussed to present data about the optimum storage condition. The chopped sardine meat was mixed with equal amount of water and $9\%$(w/w) of $75\%$ vital wheat gluten and then hydrolyzed by addition of commercial proteolytic enzymes such as bromelain, papaya protease, ficin and a enzyme mixture (Pacific Chem. Co.) for 4 hours at $52.5^{\circ}C$. The reaction mixture was heated for 30 min at $100^{\circ}C$ for enzyme inactivation, pasteurization and color development and then centrifuged for 20 min at 4,000 rpm. Table salt and benzoic acid were added for bacteriostatic effect and stored for 80 days at $15{\pm}1^{\circ}C$ and $30{\pm}1^{\circ}C$. The results were summarized as follows: 1. The amount of amino-nitrogen and pH of fish sauce were almost unchanged during storage. 2. Mininum concentration of salt for bacteriostatic activity was $9\%$(w/w) regardless of addition of benzoic acid. 3. the yields of amino-nitrogen were $63.1\%$ for the hydrolysate prepared without enzyme, $79.7\%$ for that with bromelain, $69.9\%$ with ficin, $74.3\%$ with papaya pretense, and $78.1\%$ with enzyme mixture, respectively. 4. The contents of amino-nitrogen were $4510.0mg\%$ on the dry basis for the product prepared by autolysis, $5483.2mg\%$ for that prepared with bromelain, $5305.7mg\%$ with ficin, $4994.1mg\%$ with papaya protease and $5582.3mg\%$ with the enzyme mixture, respectively. 5. The contents of crude protein were $51.35\%$ on the dry basis for the product prepared by autolysis and 55 to $59\%$ for prepared with commercial enzymes. 6. The hydrolysate prepared with the enzyme mixture revealed a little stronger meaty taste than any other products. 7. The level of crude protein in residues was still high ($69.5{\sim}77.2\%$ on the dry basis) and might be originated from the added vital wheat gluten.

• Korean Journal of Poultry Science
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• v.42 no.3
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• pp.215-221
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• 2015

Chicken breast meat samples were injected with marinade solution (salt, sugar, phosphate, monosodium glutamate, and nucleic acid) with or without 2% citrus peel extract (CPE), and then a subset were irradiated with a 1 or 2 kGy electron beam (EB) and/or subjected to high-pressure (HP) at 300 or 400 MPa. The initial total aerobic bacterial (TAB) count of the control sample was 4.57 log CFU/g and reached 7.17 log CFU/g after 3 days of storage at $4^{\circ}C$. The 2 kGy EB reduced the TAB count to 4.61 log CFU/g after 7 days. The 400 MPa HP treatment was also effective in reducing the TAB count, but the effect was slightly less than that noted with the 2 kGy EB. The CPE, in combination with the EB and HP, decreased the TAB count by 1.71 and 1.32 log CFU/g at the initial stage and further decreased the count during storage. The 2 kGy EB and the HP (300 and 400 MPa) increased the thiobarbituric acid-reactive substances value, whereas the CPE did not show an antioxidative effect. The EB and HP caused no difference in the sensory qualities. In contrast, the CPE decreased all sensory qualities tested. Sensory panelists commented that the samples with CPE were not in the "rejection" category but were "unfamiliar" for chicken breast meat. In conclusion, the EB was more effective than HP in improving the microbial quality of marinated chicken breast meat. The use of CPE in the marinade solution may synergistically increase the shelf life; however, it is necessary to develop an appropriate formulation to ensure that the sensory qualities are maintained.

• Journal of Environmental Health Sciences
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• v.36 no.3
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• pp.229-235
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• 2010

Efforts to evaluate water pollution using indicator microorganisms have been underway for decades, and driven by research on water purity control applications, water quality criteria are growing more and more strict. Furthermore, recent reports indicate that high concentrations of antibiotics are not absorbed, and are present in excrement from animals and humans dosed with unnecessarily high levels of antibiotics. This has emerged as very important issue from the standpoint of being an ecological and health hazard. In this study, water pollution was analyzed through physicochemical and microbiological means, and antibiotic resistance in indicator microorganisms was assessed. In physicochemical analysis, biochemical oxygen demand (BOD)$_5$ and chemical oxygen demand (COD)$_{Mn}$ evaluation showed that pollution by organisms was highest at the G1 location with a high human population, and the DP location which has many livestock-containing households. The indicator organism levels at the G1 location were: Total Coliforms (1205 colony forming units (CFU)/100 ml), Fecal Coliforms (270 CFU/100 ml), Escherichia coli (253 CFU/100 ml) and Fecal Streptococci (210 CFU/100 ml), while for the DP location levels were: Total Coliforms (1480 CFU/100 ml), Fecal Coliforms (438 CFU/100 ml), E. coli (560 CFU/100 ml), and Fecal Streptococci (348 CFU/100 ml). Levels of fecal indicator microorganisms such as Fecal Coliforms, E. coli and Fecal Streptococci were high at all locations in the fall (the period after the rainy season), and the yearly distribution was similar between these organisms. If the number of livestock-containing households was high, almost all strains of E. coli (as distinct from the other indicator organisms) showed resistance to antibiotics, with the degree of resistance varying between areas. E. coli strains from the OY area in particular, which has a high population density, showed strong resistance to AM10 and Va30. While strong antibiotic resistance was observed overall at the DP and OY locations, no resistance was observed at the EB location.

• Korean Journal of Microbiology
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• v.49 no.1
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• pp.30-37
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• 2013

This study was carried out to assess the spatial and tidal effects on the water quality in the lower reaches of Taewha River, Ulsan, Korea and to understand the environmental factors affecting winter algal bloom in the river. From May, 2010 to January, 2011, water samples were collected at five locations (New Samho Bridge, Old Samho Bridge, Mungjung Stream, Taewha Bridge, and Mungchon Bridge) along the river at high and low tides of spring tide. We measured environmental parameters including salinity, dissolved oxygen (DO), biological oxygen demand (BOD), chemical oxygen demand (COD), chlorophyll a (Chl a) and various nutrient concentrations. Salinity increased towards the downstream direction. Average values of Chl a concentrations ranged $10-26mg/m^3$ at high tide and $11-53mg/m^3$ at low tide depending on sampling locations. It was noteworthy that there were strong increases in Chl a concentrations during the November 21 to December 22 sampling period especially at the Taewha Bridge. At the location, Chl a concentrations were measured as $138-296mg/m^3$ for the period; Rhodomonas lacustris of class Cryptophyceae was the dominant algal species. Chl a concentrations at the Taewha Bridge were positively correlated with such parameters as salinity, BOD, DO, COD, pH, and T-N, and negatively correlated with temperature and $NO_3{^-}$-N. On the other hand, at the Mungchon Bridge the highest concentration of Chl a was $55mg/m^3$ on August 25, and Chl a concentrations were positively correlated with $NH_3$-N, T-N, $PO_4{^{3-}}$-P, T-P, and heterotrophic plate counts. The results suggested that water quality in the lower Taewha River fluctuated a lot with the sampling locations and the patterns of algal blooms were different between Taewha Bridge and Mungchon Bridge sampling locations.